Snap acting mechanism



J. P. WATSON 2,798,915

SNAP ACTING MECHANISM July 9, 1957 2 Shee ts-Sheet l Filed Jan. 4, 1954JAMES P. WA TSON 9 IN VEN TOR.

HUEBNER, BEEHLER 9 WORREL 8 HERZ/G 4' AT TOR/ 15K? July 9, 1957 J. P.WATSON SNAP ACTING MECHANISM 2 Sheets-Sheet 2 Filed Jan. 4, 1954 JAMESP. WATSON:

INVENTOR.

HUEBNER BEEHLER,

- V WORREL a! HERZ/GQ BY A TTORNEYS United States Patent O SNAP ACTINGMECHANISM James P. Watson, Lynwood, Calif. Application January 4, 1954,SerialNo. 401,768

4 Claims. Cl. 200-69) This invention relates to snap acting mechanisms,and more particularly to a snap acting switch of the type which movesabruptly from one attitude or position to another attitude or position.

It is an object of this invention to provide an improved snap actingmechanism, especially in the form of a snap acting switch, which hashigh contact pressure between theengaged portions of the switch, when inthe closed position.

It is another object of this invention to provide a snap actingmechanism which requires a relatively low force to operate, yet whichhas high contact pressure between the engaging portions of themechanism, more particularly between the contact portions of the switch.

It is another object of this invention to provide an improved snapacting mechanism, and more particularly an improved snap acting switch,having a high ratio between the contact pressure and the force requiredto operate the switch.

While it is generally recognized that it is desirable to break anelectric contact as rapidly as possible, it is often not appreciatedthat in many instances it is equally desirable to rapidly make thecontact. This is particularly true in the common incandescent houselighting where tungsten filament lamps are used, for the initial currentthrough a tungsten filament is often as high as twenty times the steadystate current, when the filament is hot. Thus as the contacts of a lampswitch approach each other, a small arc is formed which carries anextremely heavy current. Thus it is very important that the contactsengage rapidly as well as disengage rapidly. It is accordingly an objectof this invention to provide a snap acting mechanism, and moreparticularly a snap acting switch, in which a quick make-and-breakoperation is effected.

It is another object of this invention to provide an improved snapacting element suitable for use in a snap acting mechanism such as anelectric switch.

The advantages and features of the present invention have particularapplicability to the type of switch disclosed in my copending patentapplication, Serial No. 326,737, filed December 18, 1952, although thefeatures and advantages of the present invention are not limited to useor incorporation with such a switch.

In accordance with these objects and with other objects which willbecome apparent hereinafter, the present invention will now be describedwith reference to the accompanying drawings wherein:

Fig. 1 is a fragmentary external perspective view showingthe presentmechanism as it may be incorporated into the standard of a tablelarnp.

Fig. 2 is a fragmentary longitudinal section taken on line 2-2 in Fig.1.

Fig. 3 is a cross section taken on line 3--3 in Fig. 2.

Fig. 4 is a fragmentary longitudinal section taken on line 44 in Fig. 2.

Figs. 5, 6, 7 and 8 are fragmentary cross sections taken Substantiallyin the plane 4-4 of'Fig. 2.

i that lead upward from the base 16 to the bulb at the- Patented July 9,1957 Fig. 9 is a fragmentary exploded view showing the snap actingelements of the present mechanism in detail.

Fig. 10 is a fragmentary perspective View showing the cam actuatingmeans or member which operates the snap acting elements of Fig. 9.

Referring to the drawings, 16 designates the base of a table lampsurmounted by an upright standard 17, to the upper end of which issecured a lamp socket capable of receiving a two filament lamp bulb (notshown). Such lamps are known in the art and comprise two filaments ofunequal wattage, which are electrically brought out from the lamp basein the person of three terminals. Such a lamp may be operated in any oneof three modes, namely, the low Wattage filament alone, with the highwattage filament alone, or both filaments together.

Mounted within the upright standard 17 is a switch mechanism constructedin accordance with the present invention. In the example shown, thismechanism has four different positions of operation, so as to adapt itfor operating the above mentioned two-filament lamp. One of the fourpositions is the off position, while the other three positions are thethree possible combinations of lamp filament connections alluded toabove.

The switch mounted within the standard 17 is operated by a ring 18disposed circumjacent the lamp body or standard 17. The ring 18 issecured to and around the ends of an actuating shaft 19, which extendsdiametrically and horizontally across the ring 18 and through thestandard 17. The ring 18 may be manually oscillated back and forthemploying the shaft 19 as an axis, thus rocking the shaft 19 andactuating the switch mechanism within the standard 17 in a manner whichwill be described hereinafter.

, The ring 18 is secured to the shaft 19 by cooperating mating meanswhich will now be described. Embedded into the ring 18 at diametralpoints thereon, are caps 21, which have rectangular recesses 23 facingtoward the shaft 19.. The ends of the shaft 19 are relieved to formcorresponding rectangular projections 22, which engage or mate withinthe recesses 23 in the caps 21 to thus secure the ring 18 around theshaft 19. Such a construction makes possible a very simple assemblyoperation. The ring 18, being made of springable material such as metalor plastic, is simply compressed and distorted slightly as it is placedover the shaft 19, this distortion being inward at right angles totheshaft 19, so that the ring is slightly elongated in the direction of theshaft 19. When the projections 22 are opposite the recesses 23, the ring18 is released, whereupon it resumes its normal unstressed attitudecausing it to engage the shaft 19 in the manner shown in Figs. 1 and 2.The rectangular nature of the engagement between the projections 22 andrecesses 23 causes oscillation of the ring 18 to be impartedcorrespondingly to the shaft 19.

For convenience of assembly the standard 17 is made of two parts bybeing portioned along a horizontal plane 24 coinciding with thehorizontal shaft 19..

Within the standard 17 is formed a cavity through which the shaft 19passes. Within this cavity is mounted the switch mechanism of thepresent invention, shown particularly in Figs. 2, 3, and 4. The switchmechanism comprises a cylindrical insulating body 26 which substantiallyfills thecavity in the upright 17. A deep recess 27 is formed downwardlyin the body 26, which is capped by an insulating flanged cover 28. Thewalls 29 at each side of the recess 27 are slotted from the top down, tofacilitate installation of the shaft 19 in the: body 26.

Extending vertically the full length of the body 26 and throughthe cover28 are a pair of diametrically spaced bores 20, through which are passedthe wires 3 top of the standard 17, and to the switch terminals, to bedescribed hereinafter.

Also extending vertically the full length of the body 26 and cover 28are a pair of diametrically spaced peripheral grooves 25 whichaccommodate long bolts 30 that secure the upper and lower sections ofthe upright 17 together. The bolts 30 also secure the switch body 26within the standard 17.

Freely rotatably mounted over the shaft 19 is an actuating means ormember 31 embodying a clutch which selectively causes the member 31 tobe engaged or disengaged by the shaft 19. The shaft 19 is resilientlybiased to a given angular position by a pair of springs 35. The showingof these springs has been omitted from Fig. 3 in the interest ofclarity, but one such spring is shown in Fig. 2. Springs 35 bearinwardly against opposite sides of a flat lug 40 extending outward fromthe shaft 19. Springs 35 thus permit shaft 19 to oscillate, butconstantly bias it toward a central position. Such clutch and centeringmeans are of the type disclosed in the above mentioned pendingapplication, Serial No. 326,737, to which reference is hereby made forthe details thereof. The clutch portion of the actuating means or member31 is embodied in an enlarged portion 32. On the extended smallerportion of the actuating member 31 are formed a pair of actuating cams33 and 34. As best seen in Fig. 10, the cam 34 is generally cylindricalin shape and is provided with four arcuate depressions 37 spaced equallyabout the periphery thereof.

Between the depressions 37 there are thus left four equally spaced lobes39, each of which constitutes an actuating or operating member for theswitch arm, to be described hereinafter. The cam 33 is spaced axiallyfrom cam 34 and also includes four arcuate depressions 36. Thedepressions 36 are not spaced equally about the cam periphery, butinstead are spaced in pairs, the respective depressions of each pairbeing continguous and spaced substantially 45 degrees apart. That is tosay, a pair of radial lines, from the center of the shaft 19 when passedthrough the low points or centers of contiguous depressions 36 would beapproximately 45 degrees apart. On the cam 33 there are thus only twooperating lobes 38, between the two pairs of depressions 36. Betweenadjacent depressions of a given pair there is a small rounded lobe 38awhich follows the peripheral contour of the member 31, and whichcompletes the concavity of contiguous depressions 36. The lobes 38a arenot switch actuating members, however.

The lobes 38 and 39, respectively, constitute actuating, engaging, orcontact portions of the cams, respectively, which serve to actuaterespective switch elements or members, which will now be described. Thecam 33, especially its lobes 38, actuates, or operates upon, an elongateleaf spring member 41, which constitutes a first switch arm. The leafspring 41 is made of springy sheet metal and is divided into at leasttwo longitudinal portions by longitudinal slotting. In the particularembodiment shown there are two such slots 42 and 43 (Fig. 9), whichdivide the leaf spring member 41 into a plu rality, in this case three,parts or portionsa central portion 44, and another portion comprisingthe two side parts or portions 46. As shown in Fig. 9, the portions arejoined together at each end to form an integral structure constitutingthe leaf spring member 41. In the embodiment shown in Fig. 9, thecentral portion 44 is stretched longitudinally, so that it is longerthan the side portions 46 and hence must bow outwardly on one side orthe other of the plane of the shorter side portions 46, as clearly seenin Figs. -8.

The bottom end of the elongate leaf spring member 41 is bent at rightangles to form an integral base 47 which is secured to the insulatingbody 26, at the bottom of the cavity 27, through the intermediacy of aheavier metal conducting base 48, to be described. more fullyhereinafter. The free upper end of the leaf spring memr 4 her 41 isformed arcuately, as shown at 49, to constitute a movable switchcontact. The normal attitude of the leaf spring member 41, that is, theone in which it is stressed the least, is as shown in Figs. 7, 8, and 9,with the bowed portion 44 extending inwardly and with the contactportion 49 moved outwardly, away from the actuating member 31.

The free contact end 49 is thus normally in engagement with some form ofoutput member, in this case a stationary contact 51 (Fig. 4) which isdisposed against the wall of the cavity 27 near the upper end thereof,and which has a horizontal portion 52 extending into a recess on the topsurface of the insulating body 26. The portion 52 is circular and has acircular hole therethrough through which may be passed a mounting screw53 threaded into the body 26, as shown in Fig. 4. The mounting screw 53also passes through a contact grommet 54 mounted in the cap or cover 28.The grommet 54 and screw 53 thus constitute one terminal of the switchmechanism, said terminal leading directly to the stationary contact 51,selectively engageable and disengageable by the switch arm 41.

The elongate leaf spring member 41 is positioned to be actuated by thecam 33. On the other side of the shaft 19 from the member 41, but spacedaxially along the shaft, so as to be engageable by the cam 34, is asimilar leaf spring member 56. Like the leaf spring member 41, themember 56 also has a base 57, which rests atop the base 47 of the member41. The free upper end of the member 56 is likewise bent into the formof an outwardly facing are 60 which forms a movable electrical contact.This contact is normally in engagement with a stationary contact 58placed on the wall of the cavity 27 opposite the stationary contact 51but spaced axially along the shaft 19 therefrom. The stationary contact58 extends upwardly through a slot in the cover 28 and has a horizontalportion 59 extending over the top surface of the cover 28. The portion59 is secured to cover 28 by a terminal grommet 62 in which is threadeda screw 61. The grommet 62 and screw 61 constitute a second terminal ofthe switch, which leads directly to the stationary contact 58,selectively engageable by the leaf spring switch arm 56.

The cams 33 and 34 are both somewhat narrower, axially, than are therespective central sections or portions 44 and 81 of the resilient leafspring member 41 and 56. Thus as the cam actuating means or member 31 isrotated, the respective earns 33 and 34 operate only upon the respectivecentral portions of the resilient switch arms, leaving the side portionsfree of contact or engagement by the cams.

In order to rentrain the actuating means or member 31 selectively in itssevesal positions of operation, a resilient detent means or member isprovided. This means is in the form of an upright resilient arm 64 (Fig.9), which is bent outwardly and then returned to form a recessed portion66. This recessed portion is of just sufficient length to receiveresiliently one of the lobes 39 of the cam 34; and the arm 64 isdisposed opposite to the cam 34. Integral with the arm 64 is formed, atright angles thereto, a base 67, similar to the bases 47 and 57, whichoverlies the base 57, as seen in Figs. 9 and 4.

Referring to the cams 33 and 34 as pictured in Figs. 5-8, and 10, itwill be seen that there are eight different positions of operation ofthe actuating means 31 with each complete revolution thereof. Thus a 45degree rotation of the member 31 is required to move from one discreteposition to the next. Since there are four different switch combinationsof the switch arms 41 and 56, as seen in Figs. 5-8, it follows thatthere will be two complete cycles of operation with each revolution ofthe actuating member 31. In four of these discrete positions the recess66 of the detent arm 64 will be engaged by one of the lobes 39 of thecam 34, as exemplified by the positions shown in Figs. 6 and 8. In

be opposite a depression 37 of the cam 34. In such positions, however,the cam member 31 will be resiliently restrained by engagement of thebowed central portion 81 of the switch arm 56 in one of the arcuatedepressions 37 of the cam 34, as will be described more in detailhereinafter. Thus each of the eight discrete positions of the actuatingmember 31 is provided with a resilient detent means which holds themember 31 resiliently in that discrete position.

The four bases 48, 47, 57 and 67 are clamped together as shown in Fig.4- by a pair of rivets 68 (Fig. 2) which pass through pairs of holes 69formed in each of the several bases. The bases 67 and 48 are appreciablyheavier or thicker than are the bases 57 and 47 which are made of lightspring material, and thus these top and bottom bases serve as washers tointegrate the entire base assembly.

Extending upward from the bottom base 48 and integral therewith, is anelongate portion 71 which is disposed contiguous to the side wall ofthecavity 27. At the top of the insulating base or body 26, theconductor 71 is bent horizontally into a shallow recess in the topsurface of the body 26 and there terminates in an annular terminalportion 72 (Fig. 9). This portion 72 is contacted by a grommet 73 (Fig.4) mounted in the cover 28. Through the grommet '73 and terminal 72extends a terminal screw 74 threaded into the base 26, as shown in Fig.4. The screw 74 and grommet 73 constitute the third terminal of theswitch, this terminal being common to both of the movable switch arms 41and 56.

Also formed integral with the base 48 are a pair of upstanding backingmembers 76 and 77 which have projecting portions 78 and 79,respectively, engaging the respective side portions of the switch arms41 and 56, as best seen in Figs. 58. These backing members 76 and 77form fulcrums about which the resilient switch members 51 and 56 arebent.

The operation of the present snap acting mechanism will now be describedwith particular reference to Figs. 5-8. The normal position of theresilient switch arms 41 and 56that is, the position in which they arestressed the least, is that shown in Fig. 7. In this case it will benoted that the respective free ends of each of the switch arms 41 and56, are moved outward into engagement with their respective stationarycontacts 51 and 58. In this position the bowed central portion 44 of thearm 41 nests within one of the arcuate depressions 36 formed on the cam33. Similarly, the bowedcentral portion 81 of the switch arm 56 nestswith in one of the arcuate depressions 37 of the cam 34. Thus the cam 33serves as a back-up member or brace for the arm 41 which keeps the arm41 pressed firmly against the stationary contact 51. This backing actionserves to greatly enhance the contact pressure between the contact end49 of the arm 41 and the stationary contact 51. The contact pressurebetween the members 56 and 58 is similarly enhanced by the backingaction of the cam 34.

As the cam actuating means 31 is rotated clockwise from the positionshown in Fig. 7 to that shown in Fig. 8, the upper right-hand lobe 39bears against the inwardly bowed portion 81 of the arm 56 and slideslongitudinally therealong. As the lobe 39 slides along the centralportion 81, it follows an arcuate path and thus bears with increasingpressure against the central portion 81 tending to press the centralportion 81 outwardly. It has been found in practice that as the lobe 39runs along the central portion 81 and presses thereinto, a small wave isformed on the central section 81 running immediately ahead of the lobe39. When the central portion 81 has been pressed far enough outward pastthe plane of the unbowed side portions of the spring member 56, thecentral portion 81 snaps suddenly and abruptly past the dead centerposition and onto the other side of the plane Tof.the.unbowed sidesectionsof thespring arm 56. After the central portion 81 suddenly snapspast dead center, it occupies the position shown in Fig. 8.

This snapping action is simultaneously accompanied by a sudden snappingof the free end 82 of the member 56 away from its stationary contact 58,thus opening that portion of the switch mechanism. In moving from theposition shown in Fig. 7 to that shown in Fig. 8, the cam actuatingmember 31 has moved through 45 degrees. In this position, as shown inFig. 8, the lobe 39 is pressed firmly into and against the arcuate orbowed portion 81, restraining the switch arm 56 in open position againstits natural, resilient tendency to snap outward. The cam member 31 isresiliently restrained in this position by the engagement of theopposite lobe 39 in the recessed portion 66 of the resilient detent arm64.

During this operation of the cam 34 upon the central portion 81 of theswitch arm 56, the cam 33 has also moved, with respect to the bowedcentral portion 44 of the switch arm 41. This movement of the cam 33,however, has not affected the position of the switch arm 41, since thebowed portion 44 has simply moved from a nested position in one of thearcuate depressions 36 to a corresponding nested position in theimmediately adjacent depression 36, as shown in Fig. 8.

A further 45 turn of the actuating member 31 in a clockwise directionleads from the position shown in Fig. 8 to the position shown in Fig. 5.In this turn the lobe 39 steadily recedes away from the bowed centralportion 81. In this receding action the bowed portion 81 follows thelobe 39 closely by virtue of its natural resilient bias in thatdirection. When the lobe 39 has receded sufficiently, the bowed portion81 again snaps past center, i. e., past the plane of the unbowed sideportions, to the position shown in Fig. 5, whereupon, and simultaneouslytherewith, the free end 82 snaps suddenly back into engagement with itsstationary contact 58.. Thus both the make-and-break operation of theswitch arm are done abruptly and with suddenness, which is highlydesirable in switching operations, particularly when applied to tungstenincandescent illuminating bulbs.

During the movement from the position shown in Fig. 8 to that shown inFig. .5, the lobe 38 of the cam 33 is slid with increasing pressureagainst the bowed central portion 44 of the switch arm 41. As describedin connection with the lobe 39, the lobe 38 likewise rideslongitudinally against the bowed portion 44 of the arm 41 until thebowed portion snaps past center, to the position shown in Fig. 5, thissnapping being accompanied by the simultaneous snapping of the free end49 awa from its stationary contact 51. In the position shown in Fig. 5,the detent recess 66 is no longer occupied by one of the lobes 39.However, the cam actuating .member 31 is nonetheless resiliently held inthis position by the nesting of the bowed portion 81 in thecorresponding depression 37 of the cam 34.

An additional clockwise turn of 45 degrees carries the switch from theposition shown in Fig. 5 to that shown in Fig. 6, in which the bowedportions of both of the arms 41 and 56 are under pressure by theirrespective cam lobes and hence both switches are open. A further turn of45 degrees carries the switch from the position shown in Fig. 6 to thatshown in Fig. 7, where this present explanation started. It is thus seenthat four different switch combinations are effected by a degreerotation of the cam actuating member 31. Hence there are two cycles in acorrrplete revolution of the actuating member 31. t

The present invention may be practiced by elongate leaf spring memberssuch as 41, which have any number of elongate slots 42. In this case itis preferred and desirable to have a cam section operating upon eachofthe outwardly bowed portions. A multiplicity of such bowed sections ispreferred in heavy duty switches where a large contact surface isdesired between the stationary and movable contacts.

It is also within the contemplation of the present invention that wherea leaf spring member having two slots is employed, the two outersections may be the lengthened and bowed sections, if desired, leavingthe central section shorter and unbowed. In this case it is preferred tohave a pair of spaced cams operating simultaneously upon the two outerbowed sections of the leaf spring.

It is also within the contemplation of the present invention that areturn cam may be employed, i. e., a cam which bears against the unbowedportion of the leaf spring to return the spring to its position oflesser stress. For example, a pair of cams may be placed opposite and inselective engagement with the side portions 46, which bear against theleaf spring member 41 and press it back outwardly in operating from theposition shown in Fig. 6 to that shown in Fig. 7. This alternatearrangement provides a positive actuation for the switch arm, instead ofrelying on the natural resiliency thereof, to return it to the closed orouter position illustrated for example in Fig. 7.

It is further within the contemplation of the present invention that thebacking of the switch arm in its closed or engaged position, illustratedin Fig. 7, may be achieved by nesting the relaxed bowed portion of thesvw'tch in an arcuate depression which is in a stationary member, ratherthan in the rotatable cam portion of the switch. In this case therewould simply be a movable or cam portion which would project movably outfrom the stationary backing cavity in an arcuate path to actuate theswitch to its open position.

In some cases backing or reinforcing of the bowed portion may bedesirable for both positions of the switch, as for example, in a doublethrow switch where good contact pressure is desired in both throws ofthe switch arm. In this case stationary backing members with concavitiesto receive the bow may be provided on one or both sides of the switchesin position to nest with the bowed portion as it snaps back and forth.

While the instant invention has been shown and described herein in whatis conceived to be the most practical and preferred embodiments, it isrecognized that departures may be made therefrom within the scope of theinvention, which is therefore not to be limited to the details disclosedherein but is to be accorded the full scope of the claims.

Having described my invention, what I claim as new and desire to secureby Letters Patent is:

1. Actuating member comprising a body, an actuating shaft rotatablymounted in said body and protruding at each side thereof, an actuatingring of elastic material disposed circumjacent said body, and matingmeans between the ends of said shaft and diametral areas on said ring,the distance between said areas when said ring is unstressed being lessthan the length of said actuating shaft, whereby said ring may bemounted to said shaft by being distorted within the elastic limit andreleased with said mating means in mating engagement.

2. Cam actuated switch comprising in combination a pair of rotatablymounted earns, a pair of switcharms disposed, one on each side of saidcams, one of said witch arms being positioned to be actuated by one ofsaid cams and the other of said switch arms being positioned to beactuated by the other of said cams, one of said cams embodying fourdiscrete operating lobes effec tive to actuate its corresponding switcharm through four cycles with each revolution of said cam, and the otherof said cams embodying two discrete lobes effective to actuate itscorresponding switch arm through two cycles with each revolution of saidcams, whereby four different combinations of switch positions areeffected for the two switch arms.

3. Switch mechanism comprising an elongate leaf spring member composedof at least two longitudinal portions separated by a longitudinal slotand joined together at each end, one of said leaf spring portions beinglonger than the other so that it must bow out, on one side or the other,of the plane of the shorter of said portions; means mounting said leafspring member firmly at one end, the other end being free to oscillateback and forth; an electrical contact on the free end of said leafspring member; and a cam rotatably mounted on an axis substantiallytransverse to the length of said elongate spring member, andsubstantially parallel to the plane of said shorter portion of said leafspring member, said cam bearing against said bowed portion and slidinglongitudinally thereagainst with increasing pressure until said bowedportion snaps past said plane, thereby to move the free end of said leafspring member with a snap action, in a direction generally opposite tothe direction of snapping of said bowed portion, said cam having anarcuate depression with a lobe at each end thereof, said longer portionof said leaf spring member nesting within said depression and againstsaid cam in the unsnapped position of said leaf spring member.

4. Switch mechanism comprising an elongate leaf spring member composedof at least two longitudinal portions separated by a longitudinal slotand joined together at each end, one of said leaf spring portions beinglonger than the other, so that it must bow out, on one side or theother, of the plane of the shorter of said portions; means mounting saidleaf spring member firmly at one end, the other end being free tooscillate back and forth; an electrical contact on the free end of saidleaf spring member; an actuating member including a contact portionengaging the bowed portion of said leaf spring memher and mounted tomove longitudinally and inward against said bowed portion so as to slidelongitudinally therealong with increasing pressure thereagainst,starting near one end of said bowed portion and progressing toward thecenter, until said bowed portion snaps past dead center onto the otherside of the plane of said shorter portion of said leaf spring member,thereby to move the free end of said leaf spring member with a snapaction, in a direction generally opposite the direction of snapping ofsaid bowed portion; and backing means having an arcuate depressiontherein in which resides said bowed portion of said leaf spring memberwhen said actuating member is in minimum pressure engagement with saidbowed portion.

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